/*

 * Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file, and Oracle licenses the original version of this file under the BSD

 * license:

 */

/*

   Copyright 2009-2013 Attila Szegedi

*/

package jdk.dynalink;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MethodHandles.Lookup;

import java.lang.invoke.MethodType;

import java.util.Objects;

import java.util.function.Supplier;

import jdk.dynalink.linker.ConversionComparator.Comparison;

import jdk.dynalink.linker.GuardedInvocation;

import jdk.dynalink.linker.GuardingDynamicLinker;

import jdk.dynalink.linker.LinkRequest;

import jdk.dynalink.linker.LinkerServices;

import jdk.dynalink.linker.MethodHandleTransformer;

/**

 * Default implementation of the {@link LinkerServices} interface.

 */

final class LinkerServicesImpl implements LinkerServices {

    private static final ThreadLocal<SecureLookupSupplier> threadLookupSupplier = new ThreadLocal<>();

    private final TypeConverterFactory typeConverterFactory;

    private final GuardingDynamicLinker topLevelLinker;

    private final MethodHandleTransformer internalObjectsFilter;

    /**

     * Creates a new linker services object.

     *

     * @param typeConverterFactory the type converter factory exposed by the services.

     * @param topLevelLinker the top level linker used by the services.

     * @param internalObjectsFilter a method handle transformer that is supposed to act as the implementation of this

     * services' {@link #filterInternalObjects(java.lang.invoke.MethodHandle)} method.

     */

    LinkerServicesImpl(final TypeConverterFactory typeConverterFactory,

            final GuardingDynamicLinker topLevelLinker, final MethodHandleTransformer internalObjectsFilter) {

        this.typeConverterFactory = typeConverterFactory;

        this.topLevelLinker = topLevelLinker;

        this.internalObjectsFilter = internalObjectsFilter;

    }

    @Override

    public boolean canConvert(final Class<?> from, final Class<?> to) {

        return typeConverterFactory.canConvert(from, to);

    }

    @Override

    public MethodHandle asType(final MethodHandle handle, final MethodType fromType) {

        return typeConverterFactory.asType(handle, fromType);

    }

    @Override

    public MethodHandle getTypeConverter(final Class<?> sourceType, final Class<?> targetType) {

        return typeConverterFactory.getTypeConverter(sourceType, targetType);

    }

    @Override

    public Comparison compareConversion(final Class<?> sourceType, final Class<?> targetType1, final Class<?> targetType2) {

        return typeConverterFactory.compareConversion(sourceType, targetType1, targetType2);

    }

    /**

     * Used to marshal a checked exception out of Supplier.get() in getGuardedInvocation.

     */

    private static class LinkerException extends RuntimeException {

        private static final long serialVersionUID = 1L;

        public LinkerException(final Exception cause) {

            super(null, cause, true, false);

        }

    }

    @Override

    public GuardedInvocation getGuardedInvocation(final LinkRequest linkRequest) throws Exception {

        try {

            return getWithLookupInternal(() -> {

                try {

                    return topLevelLinker.getGuardedInvocation(linkRequest, this);

                } catch (final RuntimeException e) {

                    throw e;

                } catch (final Exception e) {

                    throw new LinkerException(e);

                }

            }, linkRequest.getCallSiteDescriptor());

        } catch (final LinkerException e) {

            throw (Exception)e.getCause();

        }

    }

    @Override

    public MethodHandle filterInternalObjects(final MethodHandle target) {

        return internalObjectsFilter != null ? internalObjectsFilter.transform(target) : target;

    }

    @Override

    public <T> T getWithLookup(final Supplier<T> operation, final SecureLookupSupplier lookupSupplier) {

        return getWithLookupInternal(

                Objects.requireNonNull(operation, "action"),

                Objects.requireNonNull(lookupSupplier, "lookupSupplier"));

    }

    private static <T> T getWithLookupInternal(final Supplier<T> operation, final SecureLookupSupplier lookupSupplier) {

        final SecureLookupSupplier prevLookupSupplier = threadLookupSupplier.get();

        final boolean differ = prevLookupSupplier != lookupSupplier;

        if (differ) {

            threadLookupSupplier.set(lookupSupplier);

        }

        try {

            return operation.get();

        } finally {

            if (differ) {

                threadLookupSupplier.set(prevLookupSupplier);

            }

        }

    }

    static Lookup getCurrentLookup() {

        final SecureLookupSupplier lookupSupplier = threadLookupSupplier.get();

        if (lookupSupplier != null) {

            return lookupSupplier.getLookup();

        }

        return MethodHandles.publicLookup();

    }

}